code: def normalize_target(target: str | None) -> ExtendedTarget:
      """Normalize a prediction target side."""
      if target is None:
          return SIDE_BOTH
      if target not in SIDES:
          raise ValueError(
              f"Invalid target={target}. Possible values: {SIDES}"
          )
      return cast(ExtendedTarget, target)
  
file_path: pykeen/src/pykeen/typing.py
imports: from __future__ import annotations
  from typing import Callable, Collection, Literal, Mapping, NamedTuple, Sequence, Tuple, TypeVar, Union, cast
  import numpy
  import torch
  from class_resolver import Hint, HintOrType, HintType
label_desc: Use image node_id 3 for calling a global function with example usage: normalize_target(target) and returns: cast, SIDE_BOTH